Sanctification is an immediate work of the Spirit of God on the souls of believers, purifying and cleansing of their natures from the pollution and uncleanness of sin, renewing in them the image of God, and thereby enabling them, from a spiritual and habitual principle of grace, to yield obedience unto God, according unto the tenor and terms of the new covenant, by virtue of the life and death of Jesus Christ. Or more briefly:—It is the universal renovation of our natures by the Holy Spirit into the image of God, through Jesus Christ.
The Works of John Owen, ed. William H. Goold, vol. 3: Pneumatologia: A Discourse Concerning the Holy Spirit (Edinburgh: T&T Clark, n.d.), 386.
(HT: The Old Guys)